So far I have tested the gas generator on two cars. My 2010 Camaro SS and 2006 Dodge Durango. Both cars were low pressure, the Dodge was 25psi, should be 33, the Camaro SS was 25psi, should be 36. I set the regulator to the Wagan inflator (it's not easy to get exact psi so I close the regulator). My Durango pumps everything but 33 Zero Emission. It took about 3 minutes for each hoop. The Camaro SS needed more air (25 to 36 psi), so it took about 4 minutes per tire. I have a tire pressure sensor in my car so I checked it on the way to work. The Camaro had 36psi on both passenger tires and 37psi on both driver tires, I deflated 1psi and was fine. Of course I saved a lot of time double checking when filling and I wish I had received this inflator sooner. If you want to be really accurate I'd probably buy a digital inflator, but I'm ok with that, and it has an extra LED light so inflating tires at night might be easier. If I could find a digital version for $5 more I would probably buy it, but there's nothing wrong with this inflator for the money.